Carbon fiber frame is about to fail? How does it fail, what kind of crash worst possible?

Question

I ride a carbon fiber frame road bike and was unlucky to hit a log at a very high speed (around 70km/h). I cleared the front wheel but the rear wheel really took a hit. I know that carbon fiber bikes are strong, but I would like to know what kind of warning signals should i be looking for? My rear wheel had to be replaces (hard hit) but the bike seems OK. Should I be concerned about micro cracks spreading?

Any help is appreciated. Thanks!

Thanks for the answer. I should have been a little more clear. I took the bike to the shop right away and they said it was OK... its been a few months, since the incident and I've been riding it just fine. No cracks are visible... so you think I am "in the clear"??

Thanks again.

Answer 1

Carefully inspect the entire frame for cracks. Sometimes they show themselves as fine scratches, so be careful. A magnifying glass may be helpful.

If you see ANY cracks (or possible cracks) I would take it to a shop for evaluation BEFORE riding it again.

EDIT:

There is always the possibility of something delaminating after a big hit, and it isn't always able to be detected. The most common areas after trauma are at the seat tube/top tube/seat stay junction and at the rear dropouts. You might do well to remove the seat post from the frame and "feel around" for hairline cracks.

Carbon fiber frames are good for about 15,000 to 20,000 miles if ridden carefully but I always recommend replacement or professional evaluation (includes completely tearing the bike apart and applying loads to certain parts of the frame) every 5,000 miles or 2 years.

Somehow I don't think your shop did anything except a casual inspection, so I would still inspect it myself... every inch... very carefully.

Oh.. the worst possible failure is known as SCF, or "Sudden Catastrophic Failure". SCF occurs without warning and is usually, well, catastrophic. This is most prevalent on carbon fiber and high end thin walled aluminum frames.

Answer 2

I've broken CF frames and handlebars.

The handlebar went *tink* and I had a handle in my hand.

The frame went flying with me over the front of a Mercury Grand Marquis at 20 MPH. I didn't notice a thing (Believe it or not the only damage to the bike at the time was a flat rear tire from braking like mad) but later the shop noticed a crack in the down tube during a repair to other systems. It never completely failed like the handlebar.

Answer 3

Look for micro cracks fot shure after 100 km about five times . You simply do not see inside the frames . If you do not find any micro cracks after 500 km its mean that frame is just OK . Wish you the best .

Answer 4

All good answers here. Inspect the bike on a regular basis and keep on riding. Listen for any strange new sounds when riding it may indicate partial failure which will lead to total failure as carbon doesn't bend, it breaks.

Answer 5

CF usually just breaks, and can be hard stuff. Take that bike to a bike shop.

Answer 6

Unless you see the damaged area, with CF you will never know, but it can be catastrophic and those little fibers hurt.